1. Field of the Invention
The present invention relates to an electromagnetic device and a method for producing the same. In particular, the present invention relates to a photonic-crystal electromagnetic-wave device including electromagnetic-wave absorptive portions, and a method for producing the photonic-crystal electromagnetic-wave device.
2. Description of the Related Art
In recent years, photonic crystals each having a structure in which optical properties change periodically have been receiving attention as devices capable of controlling the propagation of electromagnetic waves, in particular, light. Typically, photonic crystals are defined as structures having a periodically distributed (changed) refractive index of the constituent thereof. Photonic crystals are each an artificial material capable of achieving a novel function by changing the design of the structure.
Physical Review Letters (1987, Vol. 58, p 2059-2062) discloses that photonic crystals have photonic band gaps, as main characteristics, that forbid propagation of specific electromagnetic waves in a certain frequency or wavelength range. It is known that center positions of the photonic band gaps and widths of the gaps are controlled by appropriately adjusting structures, periods of the structures, and refractive indices of constituents of photonic crystals. Furthermore, introducing a proper defect into the refractive-index distribution of the photonic crystal results in the formation of an energy level (a defect level) due to the defect in the photonic band gap. Thereby, photonic crystals can flexibly control electromagnetic waves.
On the other hand, Japanese Patent Laid-Open No. 2003-57461 (Patent Document 1) discloses the following technique in order to provide an optoelectronic substrate for preventing electromagnetic radiation interference noise. That is, Patent Document 1 discloses a technique for inhibiting the generation of noise by forming a photonic crystal, filling part of micro-pores with a dielectric material, a conductive material, or a magnetic material, and absorbing electromagnetic waves at the micro-pores filled with the material.
In the above-described technical situation with regard to photonic crystals, when a photonic crystal is used in an electromagnetic-wave device, it is desirable to design not only the center position of the photonic band gap and the width of the gap but also structures of the band edges and the vicinity of the band edges of the photonic crystal.
However, designing only the structure of the photonic crystal, the period of the structure, and the refractive index of the material in the same way as in the known art limits control of device properties, in particular, the structures of the band edges and the vicinity of the band edges, of the photonic crystal.
Although Patent Document 1 discloses a technique for introducing portions for absorbing electromagnetic waves into the photonic crystal, the technique is not intended to control the band structure of the photonic crystal but is intended to prevent the electromagnetic radiation interference noise.